Quantifying and analysis of germination responses of annual savory (Satureja hortensis L.) to temperature and salinity stress

Nowadays medicinal plants are considered as economically important plants throughout the world، while basic information on these plants is scarce. This study was aimed to quantify germination rate response of annual savory (Satureja hortensis L.) to temperature and salinity stress. For this purpose، seeds were exposed to different temperature (12، 15، 20، 25، 30، and 35 ͦ C) and salinity levels (0، 25، 50، 75، 100، 125 and 150 m M) treatments in Seed Research Lab.، Gorgan University of Agricultural Sciences and Natural Resources in 2013. Results indicated that temperature and salinity stress simple and interacted effects had significant effect on maximum germination percentage (MGR)، germination rate (reciprocal time to 50% germination)، and time elapsed to reach 10، 50 and 90% germination. Along with salinity levels increment، both germination percentage and rate decreased. With temperature increasing to optimum temperature، both germination percentage and rate increased، while it decreased from optimum temperature onward. Assessment of three nonlinear regression models including segmented، dent-like and beta models revealed that the last one was the superior model. Base on the superior model (Beta)، base، the optimum and ceiling temperatures were estimated as 8، 24. 77 and 41 ͦ C، respectively. Biological hours for control treatment (zero salinity level) were calculated as 83. 68 hours. Optimum and ceiling temperatures were not affected by salinity stress، but base temperature and biological hours for germination was delayed as 1. 35 ͦC decrement and 1. 65 hours increment per each 25 m molar salinity levels.